Ethylene-Propylene Copolymeric Compositions With Long Methylene Sequence Lengths

ABSTRACT

This invention relates to methods to prepare and compositions pertaining to branched ethylene-propylene copolymers that include at least 50% ethylene content by weight as determined by FTIR; a g′ vis  of less than 0.95; a M W  of 150,000 to 250,000; a methylene sequence length of 6 or greater as determined by  13 C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%; and can have greater than 50% vinyl chain end functionality.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to “Substituted Metallocene Catalysts”, U.S. Ser. No. 61/847,442 filed Jul. 17, 2013; and claims priority to U.S. Ser. No. 61/847,467 filed Jul. 17, 2013, which is herein incorporated by reference.

FIELD OF THE INVENTION

Branched ethylene-propylene copolymers with a high degree of branching (g′ of less than 1) and having 50 to 55 weight percent ethylene content as measured by ¹³C NMR are described. The copolymers can be used as compatibilizers for polymer blends.

BACKGROUND OF THE INVENTION

Alpha-olefins, especially those containing 6 to 20 carbon atoms, have been used as intermediates in the manufacture of detergents or other types of commercial products. Such alpha-olefins have also been used as monomers, especially in linear low density polyethylene. Commercially produced alpha-olefins are typically made by oligomerizing ethylene. Longer chain alpha-olefins, such as vinyl-terminated polyethylenes are also known and can be useful as building blocks following functionalization or as macromonomers.

Some relevant publications includes U.S. Pat. No. 4,814,540; JP 2005-336092 A2; US 2012-0245311 A1; Rulhoff et al. in 16 MACROMOLECULAR CHEMISTRY AND PHYSICS 1450-1460 (2006); Kaneyoshi et al. in 38 MACROMOLECULES 5425-5435 (2005); Teuben et al. 62 J. MOL. CATAL. 277-287 (1990); X. Yang et al., 31 ANGEW. CHEM. INTL ED. ENGL. 1375-1377 (1992); Resconi et al. in 114 J. AM. CHEM. SOC. 1025-1032 (1992); Small and Brookhart 32 MACROMOLECULES 2120-2130 (1999); Weng et al., 21 MACROMOL RAPID COMM. 1103-1107 (2000); 33 MACROMOLECULES 8541-8548 (2000); Moscardi et al. in 20 ORGANOMETALLICS 1918-1931 (2001); Coates et al. in 38 MACROMOLECULES 6259-6268 (2005); Rose et al. 41 Macromolecules 559-567 (2008); Zhu et al., 35 Macromolecules 10062-10070(2002) and 24 MACROMOLECULES RAP. COMMUN. 311-315 (2003); Janiak and Blank in 236 MACROMOL. SYMP. 14-22 (2006). Other references include U.S Ser. No. 13/072,280 filed Mar. 25, 2011, published on 9/27/2012 and USSN 61/467681 filed 3/25/11, published on Sep. 27, 2012 also relate to olefin polymerization, particularly to produce vinyl terminated polymers.

However, few catalysts/processes have been shown to produce branched chain unsaturations in high yields, a wide range of molecular weight, and with high catalyst activity for propylene-based polymerizations. The physical properties of branched oligomer and polymers have attracted considerable attention. Branching in an oligomer or a polymer can result in solution and solid-state properties markedly different than those of its linear counterpart. Accordingly, there is need for new catalysts and/or processes that produce branched polymers in high yields, with a wide range of molecular weight, and with high catalyst activity.

SUMMARY OF THE INVENTION

Branched amorphous ethylene-propylene oligomers and polymers, and compositions comprising such branched amorphous ethylene-propylene oligomers and polymers are described. The branched ethylene-propylene copolymers include one or more of the following: at least 50% ethylene content by weight as determined by FTIR; a g′_(vis) of less than 0.98; a M_(W) of 150,000 to 250,000; a methylene sequence length of 6 or greater as determined by ¹³C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%; and greater than 50% vinyl chain end functionality. Processes, preferably homogenous processes, for making the branched ethylene-propylene oligomers and polymers are described, wherein the processes comprise contacting ethylene and propylene with a catalyst system, comprising an activator and at least one metallocene.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 provides mEPCs made by catalyst 1/activator 1 have much higher melting points than mEPCs made by catalyst 2/activator 2.

FIG. 2 demonstrates that mEPCs made by catalyst 1/activator 1 have higher heats of fusion than mEPCs made by catalyst 2/activator 2.

FIG. 3(a-c) is a GPC-3D curve for sample 1 prepared with catalyst 2/activator 2. Run conditions and instrument and polymer parameters: Inject Mass (mg) =0.2784; Calc. Mass (mg) =0.256 (91.9%); Adjusted Flow Rate (ml/m) =0.543; Column Cal. CO =12.474; Column Cal. C1=−0.31335; Column Cal. C2=−0.0025044; Column Cal. C3=0; Inject Mark (ml)=31.837; Vistalon B1=0.953; Random Coil Analysis (5); A2 (Input Value)=0.00106; (dn/dc)=0.104; LS to DRI (ml)=0.152; LS to Vis. (ml) =0.385; K (sample)=0.00042613; alpha (sample)=0.699; LS Calib. Const.=1.5348e-05; DRI Const.=3.364e-05; DP Const.=0.8722; IP Baseline=27.3 KPa.

FIG. 4 (a-c) is a GPC-3D curve for sample 2 prepared with catalyst 1/ activator 1. Run conditions and instrument and polymer parameters: Inject Mass (mg)=0.46; Calc. Mass (mg)=0.415 (90.2%); Adjusted Flow Rate (ml/m)=0.543; Column Cal. C0=12.474; Column C1=−0.31335; Column Cal. C2=−0.0025044; Column Cal. C3=0; Inject Mark (ml)=31.837; Vistalon B1=0.846; Random Coil Analysis (5); A2 (Input Value=0.001033; (dn/dc)=0.104; LS to DRI (ml)=0.152; LS to Vis. (ml)=0.385; K (sample) =0.00041796; alpha (sample) =0.699; LS Calib. Const. =1.5348e-05; DRI Const.=3.364e-05; DP Const. =0.8722; IP Baseline =27.3 KPa.

FIG. 5 (a-c) is a GPC-3D curve for sample 3 prepared with catalyst 1/activator 1. Run conditions and instrument and polymer parameters: Inject Mass (mg)=0.267; Calc. Mass (mg)=0.286 (107%); Adjusted Flow Rate (ml/m)=0.543; Column Cal. C0=12.474; Column Cal. C1=−0.31335; Column Cal. C2=−0.0025044; Column Cal. C3=0; Inject Mark (ml)=31.837; Vistalon B1=0.916; Random Coil Analysis (5); A2 (Input Value)=0.001048; (dn/dc)=0.104; LS to DRI (ml)=0.152; LS to Vis. (ml)=0.392; K (sample)=0.00042251; alpha (sample)=0.699; LS Calib. Const.=1.5333e-05; DRI Const.=3.605e-05; DP Const.=0.9328; IP Baseline =28.3 KPa.

FIG. 6 are representative stress-strain curves of mEPCs measured at room temperature and a pull rate of 5.08 cm/min

FIG. 7a provides Van Gurp-Palmen plots of mEPCs prepared with catalyst 1/activator 1.

FIG. 7b provides Van Gurp-Palmen plots of mEPCs prepared with catalyst 2/activator 2.

FIG. 8a provides the complex viscosity versus frequency of mEPCs prepared with catalyst 1/activator 1.

FIG. 8b provides the complex viscosity versus frequency of mEPCs prepared with catalyst 2/activator 2.

DETAILED DESCRIPTION

Described herein are branched ethylene-propylene oligomers and polymers and processes to produce the branched ethylene-propylene oligomers and polymers and compositions. “Branched” as used herein means a polyolefin having a g′_(vis) of 0.98 or less.

These branched polyolefins having high amounts of allyl chain ends may find utility as macromonomers for the synthesis of polyolefins, such as linear low density polyethylene, block copolymers, and as additives, for example, as additives to, or blending agents in, lubricants, waxes, and adhesives. Advantageously, when used as an additive, such as to film compositions, the branched nature of these polyolefins may improve rheological properties in molten state and desired mechanical properties by allowing optimal thermoforming and molding at lower temperatures, thereby reducing energy consumption of the film forming process, as compared to linear polyolefin analogues. Additionally, the high amounts of allyl chain ends of these branched polyolefins provides a facile path to functionalization. The functionalized branched polyolefins may be also useful as additives or blending agents.

The branched ethylene-propylene copolymers include one or more of the following: at least 50% ethylene content by weight as determined by FTIR; a g′_(vis) of less than 0.98; a M_(w) of 150,000 to 250,000; a methylene sequence length of 6 or greater as determined by ¹³C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%; and greater than 50% vinyl chain end functionality.

The ethylene-propylene copolymer comprise ethylene derived units, as determined by FTIR, within the range of from 30 or 40 or 50 wt % to at least 55 or 60 or 65 wt % by weight of the copolymer, or alternatively the weight percent of ethylene in the ethylene-propylene copolymer is at least 50 wt %, more particularly from 50 wt % to 55 wt %, the remainder being propylene-derived units.

An “olefin,” alternatively referred to as “alkene,” is a linear, branched, or cyclic compound of carbon and hydrogen having at least one double bond. For purposes of this specification and the claims appended thereto, when a polymer or copolymer is referred to as comprising an olefin, including, but not limited to ethylene and propylene, the olefin present in such polymer or copolymer is the polymerized form of the olefin. For example, when a copolymer is said to have an “ethylene” content of 50 wt % to 55 wt %, it is understood that the mer unit in the copolymer is derived from ethylene in the polymerization reaction and said derived units are present at 50 wt % to 55 wt %, based upon the weight of the copolymer. A “polymer” has two or more of the same or different mer units. A “homopolymer” is a polymer having mer units that are the same. A “copolymer” is a polymer having two or more mer units that are different from each other. A “terpolymer” is a polymer having three mer units that are different from each other. “Different” as used to refer to mer units indicates that the mer units differ from each other by at least one atom or are different isomerically. Accordingly, the definition of copolymer, as used herein, includes terpolymers and the like. An oligomer is typically a polymer having a low molecular weight (such an Mn of less than 25,000 g/mol, preferably less than 2,500 g/mol) or a low number of mer units (such as 75 mer units or less).

As used herein the term “branched oligomer or branched polymer” is defined as the polymer molecular architecture obtained when an oligomer (or a polymer) chain (also referred to as macromonomer) with reactive polymerizable chain ends is incorporated into another oligomer/polymer chain during the polymerization of the latter to form a structure comprising a backbone defined by one of the oligomer chains with branches of the other oligomer chains extending from the backbone. A linear oligomer differs structurally from the branched oligomer because of lack of the extended side arms. For some catalyst systems, the oligomer with a reactive polymerizable chain end can be generated in-situ and incorporated into another growing chain to form a homogeneous branched oligomers in a single reactor. A linear polymer has a branching index (g′_(vis)) of 0.98 or more, preferably 0.99 or more, preferably 1.0 (1.0 being the theoretical limit of g′_(vis)).

The inventive ethylene-propylene polymers disclosed herein are branched, having a branching index (g′_(vis)) of less than 0.98 (preferably 0.95 or less, preferably 0.90 or less, even more preferably 0.85 or less).

The inventive copolymers also have a methylene sequence length of 6 or greater as determined by ¹³C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%.

Preferably, the heat of fusion of the ethylene-propylene copolymer has a heat of fusion (AH_(f)) of from 5 or 10 or 12 or 16 J/g to 30 or 40 or 50 J/g. The inventive ethylene-propylene copolymer also have at least 50% allyl chain ends, relative to total unsaturated chain ends (preferably 60% or more, preferably 70% or more, preferably 75% or more, preferably 80% or more, preferably 90% or more, preferably 95% or more).

The ethylene-propylene copolymers described herein can also have one or more of the following characteristics.

In one embodiment, the branched ethylene-propylene copolymers described herein have a Mw/Mn range of from 2.2 to 2.6. Preferably, the Mw/Mn is less than 2.4. Both Mn and Mw are determined using GPC-DRI.

In one aspect, the branched ethylene-propylene copolymers described herein have a Mooney viscosity (ML) ML (1+4) at 125° C. of from 29 to 100 MU (preferably from 40 to 82; preferably from 50 to 68), where MU is Mooney Units.

In another aspect, the branched ethylene-propylene copolymers described herein have a Mooney large relaxation area (MLRA) of from 100 to 1000 (preferably from 175 to 610; preferably from 275 to 545; preferably from 325 to 530).

In still another aspect, the branched ethylene-propylene copolymers described herein have a melting point (Tm) within the range of from −30 or −20 or −10° C. to 10 or 20 or 30 or 40° C.

In yet another aspect, the branched ethylene-polymer copolymers described herein have an elongation (break) of 150% or greater and/or a nomial stress range of from 0.22 MPa to 0.32 MPa at 50% strain and/or 0.15 MPa to 0.2 MPa at 150% strain, at a pull rate of 5.08 centimeters/minute.

In an embodiment, the branched ethylene-propylene copolymers described herein have a phase angle of 50° at 8000 G*Pa and 25° at 500,000 G*Pa at 190° C.

In another embodiment, the branched ethylene-propylene copolymers herein have a phase angle of 45° at 10,000 G*Pa and a range of 25° to 35° at 100,000 G*Pa at 190° C.

In still another embodiment, the branched ethylene-propylene copolymers herein have an average sequence length for methylene sequences two and longer of from 8 to 9.

In still yet another embodiment, the branched ethylene-propylene copolymers herein have an average sequence length for methylene sequences six and longer of from 12 to 14.

In yet another aspect, the branched ethylene-propylene copolymers have an r₁r₂ of from 2.7 to 2.8.

In some embodiments, the branched polymers have 50% or greater allyl chain ends (preferably 60% or more, preferably 70% or more, preferably 80% or more, preferably 90% or more, preferably 95% or more). Branched polymers generally have a chain end (or terminus) which is saturated and/or an unsaturated chain end. The unsaturated chain end of the inventive polymers comprises “allyl chain ends.” An allyl chain end is represented by the formula:

where “P” represents the rest of polymer chain. “Allylic vinyl group,” “allyl chain end,” “vinyl chain end,” “vinyl termination,” “allylic vinyl group” and “vinyl terminated” are used interchangeably in the following description.

The unsaturated chain ends may be further characterized by using bromine electrometric titration, as described in ASTM D 1159. The bromine number obtained is useful as a measure of the unsaturation present in the sample. In embodiments herein, branched polyolefins have a bromine number which, upon complete hydrogenation, decreases by at least 50% (preferably by at least 75%).

The inventions described herein relate to branched ethylene-propylene polymers and polymerization processes to produce them, wherein the formation of polymers with an allyl chain end and reinsertion of oligomers with allyl chain ends into another oligomer take place in the same polymerization zone or in the same reactor. Preferably a single catalyst system is used, more preferably two different metallocene catalysts are used in combination, and most preferably, two different metallocene catalysts wherein one is a symmetrical metallocene (meaning that both cyclopentadienyl groups are the same) and the other unsymmetrical (meaning that each of the two cyclopentadienyl groups are different). The catalyst system is capable of producing an oligomer with allyl chain end and reinserting the oligomer into another oligomer to form a branched polymer.

Processes, preferably homogenous processes, for making the branched ethylene-propylene oligomers and polymers are described, wherein the processes comprise contacting ethylene and propylene with a catalyst system, comprising an activator and at least one metallocene.

Suitable indenyl metallocene catalysts, activators and catalyst systems useful herein are those described herein below as well as those described in attorney docket number 2013EM185 filed concurrently herewith.

Suitable catalysts include, for example, rac-tetramethylenesilylene-bis(2,4,7-trimethylindenyl)hafnium (IV) dimethyl. Suitable activators include, for example, dimethylanilinium tetrakisperfluoronaphthylborate.

Conversion is the amount of monomer and comonomers that are converted to polymer products, and is reported as weight percent and is calculated based on the polymer yield and the amount of monomer fed into the reactor.

Catalyst activity (also referred to as catalyst productivity) is a measure of amount of polymer product produced by unit weight of the catalyst in a given time period. For a continuous process, the catalyst activity is reported as the kilogram of polymer product (P) produced per kilogram of catalyst (cat) used (kgP/kgcat). In a batch process, catalyst activity is reported as the grams of polymer product produced per gram of catalyst and per hour (g P/g cat Hr).

The processes described herein can be run at temperatures and pressures suitable for commercial production of the branched ethylene-propylene polymers. Typical temperatures and/or pressures include a temperature greater than 35° C. (preferably in the range of from 35 to 150° C., from 40 to 140° C., from 60 to 140° C., or from 80 to 130° C.) and a pressure in the range of from 0.1 to 10 MPa (preferably from 0.5 to 6 MPa or from 1 to 4 MPa).

The processes described herein have a residence time suitable for commercial production of the branched ethylene-propylene polymers. In a typical polymerization, the residence time of the polymerization process is up to 300 minutes, preferably in the range of from 5 to 300 minutes, preferably from 10 to 250 minutes, preferably from 10 to 120 minutes, or preferably from 10 to 60 minutes. At a given feed condition, long residence time may increase the monomer conversion, thereby increasing the oligomer concentration and decreasing the monomer concentration in a reactor. This will enhance the level of branching of the oligomer. In one embodiment, the residence time is used to control the branching level and to optimize the branching structures for specific end-uses.

The polymer product can be recovered from solution at the completion of the polymerization by any of the techniques well known in the art such as steam stripping followed by extrusion drying or by devolatilizing extrusion. Separated solvent/diluent and monomers can be recycled back in the reactor.

In a most preferred embodiment, two different metallocene/activator systems, rac-tetramethylenesilylene-bis(2,4,7-trimethylindenyl)hafnium (IV) dimethyl (catalyst 1)/dimethylanilinium tetrakisperfluoronaphthylborate (activator 1) and bis(para-triethylsilylphenyl)methylene(2,7-di-tert-butyl-fluoren-9-yl)(cyclopentadienyl)hafnium(IV) dimethyl (catalyst 2)/dimethylanilinium tetrakisperfluorophenylborate (activator 2), were used to prepare ethylene-propylene copolymers. At similar nominal ethylene content, two different types of copolymer sequence distributions were obtained. At an ethylene content of 55 wt %, the mEPC prepared with catalyst 1/activator 1 has, on average, longer methylene sequences based on ¹³C NMR studies, leading to a melting point (T_(m)) of 30° C. higher than the mEPC prepared with catalyst 2/activator 2. The former copolymer also has better tensile properties, a higher melt strength and a higher degree of shear thinning due to the presence of branching, as demonstrated by Mooney viscosity, GPC-3D, and ¹H NMR.

EXAMPLES

In conducting the ¹³C NMR investigations, samples were dissolved in tetrachloroethane-d2 at concentrations between 10 to 15 wt % in a 10 mm NMR tube. ¹³C NMR data was collected at 120° C. using a Varian spectrometer with a ¹H frequency of at least 400 MHz. A 90 degree pulse, an acquisition time adjusted to give a digital resolution between 0.1 and 0.12 Hz, at least a 10 second pulse acquisition delay time with continuous broadband proton decoupling using swept square wave modulation without gating was employed during the entire acquisition period. The spectra were acquired using time averaging to provide a signal to noise level adequate to measure the signals of interest.

Prior to data analysis, spectra were referenced by setting the chemical shift of the (—CH₂—)_(n) (where n>6) signal to 29.9 ppm.

Chain ends for quantization were identified using the signals shown in the table below. N-butyl and n-propyl were not reported due to their low abundance (less than 5%) relative to the chain ends shown in the table below.

Chain end ¹³CNMR Chemical shift P~i-Bu 23.5 to 25.5 and 25.8 to 26.3 ppm E~i-Bu 39.5 to 40.2 P~Vinyl 41.5 to 43 E~Vinyl 33.9 to 34.4

The number of vinyl chain ends, vinylidene chain ends and vinylene chain ends is determined using ¹H NMR using deuterated tetrachloroethane as the solvent on an at least 250 MHz NMR spectrometer, and in selected cases, confirmed by ¹³C NMR. Proton NMR data was collected at either room temperature or 120° C. (for purposes of the claims, 120° C. shall be used) in a 5 mm probe using a Varian spectrometer with a ¹H frequency of at least 400 MHz. Data was recorded using a maximum pulse width of 45° C., 8 seconds between pulses and signal averaging 120 transients. Spectral signals were integrated and the number of unsaturation types per 1000 carbons was calculated by multiplying the different groups by 1000 and dividing the result by the total number of carbons. The number averaged molecular weight (Mn) was calculated by dividing the total number of unsaturated species into 14,000, assuming one unsaturation per polyolefin chain.

The chain end unsaturations are measured as follows. The vinyl resonances of interest are between from 5.0 to 5.1 ppm (VRA), the vinylidene resonances between from 4.65 to 4.85 ppm (VDRA), the vinylene resonances from 5.31 to 5.55 ppm (VYRA), the trisubstituted unsaturated species from 5.11 to 5.30 ppm (TSRA) and the aliphatic region of interest between from 0 to 2.1 ppm (IA). The number of vinyl groups/1000 Carbons is determined from the formula:

(VRA*500)/(((IA+VRA+VYRA+VDRA)/2)+TSRA).

Likewise, the number of vinylidene groups/1000 Carbons is determined from the formula:

(VDRA*500)/(((IA+VRA+VYRA+VDRA)/2)+TSRA),

the number of vinylene groups/1000 Carbons from the formula

(VYRA*500)/(((IA +VRA+VYRA+VDRA)/2)+TSRA)

and the number of trisubstituted groups from the formula

(TSRA*1000)/(((IA+VRA+VYRA+VDRA)/2)+TSRA).

VRA, VDRA, VYRA, TSRA and IA are the integrated normalized signal intensities in the chemical shift regions defined above.

Molecular weights (number average molecular weight (Mn), weight average molecular weight (Mw), and z-average molecular weight (Mz)) were determined using a Polymer Laboratories Model 220 high temperature SEC equipped with on-line differential refractive index (DRI), light scattering (LS), and viscometer (VIS) detectors. It used three Polymer Laboratories PLgel 10 m Mixed-B columns for separation using a flow rate of 0.54 ml/min and a nominal injection volume of 300 μL. The detectors and columns were contained in an oven maintained at 135° C. The stream emerging from the SEC columns was directed into a miniDAWN optical flow cell and then into the DRI detector. The DRI detector was an integral part of the Polymer Laboratories SEC. The viscometer was inside the SEC oven, positioned after the DRI detector. The details of these detectors as well as their calibrations have been described by, for example, T. Sun, P. Brant, R. R. Chance, and W. W. Graessley, in Macromolecules, Volume 34, Number 19, 6812-6820, (2001), incorporated herein by reference.

Solvent for the SEC experiment was prepared by dissolving 6 grams of butylated hydroxy toluene as an antioxidant in 4 liters of Aldrich reagent grade 1, 2, 4-trichlorobenzene (TCB). The TCB mixture was then filtered through a 0.7 μm glass pre-filter and subsequently through a 0.1 μm Teflon filter. The TCB was then degassed with an online degasser before entering the SEC. Polymer solutions were prepared by placing dry polymer in a glass container, adding the desired amount of TCB, then heating the mixture at 160° C. with continuous agitation for 2 hours. All quantities were measured gravimetrically. The TCB densities used to express the polymer concentration in mass/volume units were 1.463 g/mL at room temperature and 1.324 g/mL at 135° C. The injection concentration was from 1.0 to 2.0 mg/mL, with lower concentrations being used for higher molecular weight samples. Prior to running each sample the DRI detector and the injector were purged. Flow rate in the apparatus was then increased to 0.5 mL/minute, and the DRI was allowed to stabilize for 8 to 9 hours before injecting the first sample. The concentration, c, at each point in the chromatogram was calculated from the baseline-subtracted DRI signal, I_(DRI), using the following equation:

K _(DRI) I _(DRI)/(dn/dc)

where K_(DRI) is a constant determined by calibrating the DRI, and (dn/dc) is the refractive index increment for the system. The refractive index, n=1.500 for TCB at 135° C. and λ=690 nm. For purposes herein and the claims thereto (dn/dc)=0.104 for propylene polymers and 0.1 otherwise. Units of parameters used throughout this description of the SEC method are: concentration is expressed in g/cm³, molecular weight is expressed in g/mol, and intrinsic viscosity is expressed in dL/g.

The light scattering detector was a high temperature mini DAWN (Wyatt Technology, Inc.). The primary components are an optical flow cell, a 30 mW, 690 nm laser diode light source, and an array of three photodiodes placed at collection angles of 45°, 90°, and 135°. The molecular weight, M, at each point in the chromatogram was determined by analyzing the LS output using the Zimm model for static light scattering (M. B. Huglin, LIGHT SCATTERING FROM POLYMER SOLUTIONS, Academic Press, 1971):

$\frac{K_{o}c}{\Delta \; {R(\theta)}} = {\frac{1}{{MP}(\theta)} + {2A_{2}c}}$

Here, ΔR(θ) is the measured excess Rayleigh scattering intensity at scattering angle 0, c is the polymer concentration determined from the DRI analysis, A₂ is the second virial coefficient (for purposes herein, A₂=0.0006 for propylene polymers, 0.0015 for butene polymers and 0.001 otherwise), (dn/dc)=0.104 for propylene polymers, 0.098 for butene polymers and 0.1 otherwise, P(θ) is the form factor for a monodisperse random coil, and K_(o) is the optical constant for the system:

$K_{o} = \frac{4\pi^{2}{n^{2}\left( {{dn}/{dc}} \right)}^{2}}{\lambda^{4}N_{A}}$

where N_(A) is Avogadro's number, and (dn/dc) is the refractive index increment for the system. The refractive index, n =1.500 for TCB at 145° C. and =690 nm.

A high temperature viscometer from Viscotek Corporation was used to determine specific viscosity. The viscometer has four capillaries arranged in a Wheatstone bridge configuration with two pressure transducers. One transducer measures the total pressure drop across the detector, and the other, positioned between the two sides of the bridge, measures a differential pressure. The specific viscosity, η_(s), for the solution flowing through the viscometer was calculated from their outputs. The intrinsic viscosity, [η], at each point in the chromatogram was calculated from the following equation:

η_(s) =c[η]+0.3(c[η])²

where c is concentration and was determined from the DRI output.

The branching index (g′_(vis)) is defined as the ratio of the intrinsic viscosity of the branched polymer to the intrinsic viscosity of a linear polymer of equal molecular weight and same composition, and was calculated using the output of the SEC-DRI-LS-VIS method as follows. The average intrinsic viscosity, [η]_(avg), of the sample was calculated by:

$\lbrack\eta\rbrack_{avg} = \frac{\sum{c_{i}\lbrack\eta\rbrack}_{i}}{\sum c_{i}}$

where the summations are over the chromatographic slices, i, between the integration limits

The branching index g′_(vis) is defined as:

$g_{vis}^{\prime} = \frac{\lbrack\eta\rbrack_{avg}}{{kM}_{v}^{\alpha}}$

The intrinsic viscosity of the linear polymer of equal molecular weight and same composition was calculated using the Mark-Houwink equation. For purpose of the embodiments described herein and claims thereto, k=0.000579 and α=0.695 for ethylene polymers, k=0.0002288 and α=0.705 for propylene polymers, and k=0.00018 and α=0.7 for butene polymers. For EP, the values of k and a are determined based on the ethylene/propylene composition using a standard calibration procedure such that: k=(1−0.0048601EP −6.8989×10⁻⁶EP²)×5.79×10⁻⁴(200,000)^(—Trunc) ^((0.1EP)) ^(/1000) and α=0.695+Trunc(0.1EP)/1000, where EP is the weight percent of propylene in the EP, and Trunc indicates that only the integer portion is kept in the calculation. For example, Trunc(5.3)=5. M_(v) is the viscosity-average molecular weight based on molecular weights determined by LS analysis. See Macromolecules, 2001, 34, pp. 6812-6820 and Macromolecules, 2005, 38, pp. 7181-7183, for guidance on selecting a linear standard having similar molecular weight and comonomer content, and determining k coefficients and a exponents. The molecular weight data reported here are those determined using GPC DRI detector, unless otherwise noted.

Viscosity was measured using a Brookfield Viscometer according to ASTM D-3236.

Peak melting point, Tm, (also referred to as melting point), peak crystallization temperature, Tc, (also referred to as crystallization temperature), glass transition temperature (Tg), heat of fusion (ΔH_(f)), and percent crystallinity were determined using the following DSC procedure according to ASTM D3418-03. Differential scanning calorimetric (DSC) data were obtained using a TA Instruments model Q200 machine. Samples weighing approximately 5-10 mg were sealed in an aluminum hermetic sample pan. The DSC data were recorded by first gradually heating the sample to 200° C. at a rate of 10° C./minute. The sample was kept at 200° C. for 2 minutes, then cooled to −90° C. at a rate of 10° C./minute, followed by an isothermal for 2 minutes and heating to 200° C. at 10° C./minute. Both the first and second cycle thermal events were recorded. Areas under the endothermic peaks were measured and used to determine the heat of fusion and the percent of crystallinity. The percent crystallinity is calculated using the formula, [area under the melting peak (Joules/gram)/B (Joules/gram)] *100, where B is the heat of fusion for the 100% crystalline homopolymer of the major monomer component. These values for B are to be obtained from the Polymer Handbook, Fourth Edition, published by John Wiley and Sons, New York 1999, provided however that a value of 189 J/g (B) is used as the heat of fusion for 100% crystalline polypropylene, a value of 290 J/g is used for the heat of fusion for 100% crystalline polyethylene. The melting and crystallization temperatures reported here were obtained during the second heating/cooling cycle unless otherwise noted.

All of the examples were produced in a 1-liter, solution-phase continuous stirred tank reactor. The reactor temperature was controlled by metering a mixture of chilled water and steam to the reactor jacket, and reactor pressure was maintained by adjusting the set pressure on a back-pressure regulator downstream of the reactor. Raw materials (ethylene, propylene, isohexane, and toluene) were obtained from an integrated pipeline source.

Isohexane and toluene were further purified by passing the material through a series of adsorbent columns containing either 3A mole sieves (isohexane) or 13X mole sieves (toluene) followed by treatment with alumina. Ethylene and propylene monomers were purified on-line by passing the feed streams through beds of 3A mole sieves, and metered to a mixing manifold using mass flow controllers (Brooks), where they were combined with the isohexane solvent prior to entering the reactor. Separate feeds of scavenger (tri-n-octyl aluminum in isohexane) and catalyst (premixed with activator in toluene), were also supplied to the reactor. Nominal reactor residence times were on the order of 10 minutes, after which the continuous reactor effluent was collected and first air-dried in a hood to evaporate most of the solvent and unreacted monomers, and then dried in a vacuum oven at a temperature of 80° C. for 12 hours. The vacuum oven dried samples were then weighed to obtain the final polymer yield which could then be used to calculate catalyst activity (also referred as to catalyst productivity) based on the ratio of yield to catalyst feed rate.

Two different metallocene/activator systems, catalyst 1/activator 1 and catalyst 2/activator 2, were used to prepare ethylene/propylene copolymers (metallocene derived ethylene/propylene copolymers, “mEPCs”) with various ethylene contents in a semi-continuous lab reactor. The process conditions and the characterization of some mEPCs prepared with catalyst 1/activator 1 are shown in Table 1.

The polymer C₂ wt % was measured by FTIR, ASTM D3900.

LS and DRI denote the methods of light scattering and differential refractive index used in the GPC-3D experiment, respectively.

ML is the Mooney viscosity and MLRA is the Mooney large relaxation area for 100 s, both measured at 125° C.

Processability is arguably one of the most important and critical properties of rubber and rubber compounds. Mooney viscosity is a property used to monitor the quality of both natural and synthetic rubbers. It measures the resistance of rubber to flow at a relatively low shear rate. The highly branched compositions herein have a Mooney viscosity ML (1+4) at 125° C. of 30 to 100 MU (preferably 40 to 100; more preferably 50 to 100; even more preferably 60 to 100), where MU is Mooney Units.

While the Mooney viscosity indicates the plasticity of the rubber, the Mooney relaxation area (MLRA) provides a certain indication of the effects of molecular weight distribution and elasticity of the rubber. The highly branched compositions also have a MLRA of 100 to 1000 (preferably 200 to 1000; more preferably 300 to 1000; even more preferably 450 to 950).

Another indication of melt elasticity is the ratio of MLRA/ML. This ratio has the dimension of time and can be considered as a “relaxation time.” A higher number signifies a higher degree of melt elasticity. Long chain branching will slow down the relaxation of the polymer chain, hence increasing the value of MLRA/ML. The highly branched compositions of this invention preferably have an MLRA/ML ratio greater than 5, preferably greater than 6, preferably greater than 7 and most preferably greater than 8, preferably for mEPCs with a Mw/Mn from 2 to 3 or 4, higher than the precursor mEPDM rubber, or desirably, the MLRA/ML ratio is within a range of from 5 or 6 to 10 or 12 or 14.

Mooney viscosity and Mooney relaxation area are measured using a Mooney viscometer, operated at an average shear rate of 2 s⁻¹, according to the following modified ASTM D1646.

ASTM D1646 was modified as follows: A square of sample is placed on either side of the rotor. The cavity is filled by pneumatically lowering the upper platen. The upper and lower platens are electrically heated and controlled at 125° C. The torque to turn the rotor at 2 rpm is measured by a torque transducer. The sample is preheated for 1 minute after the platens were closed. The motor is then started and the torque is recorded for a period of 4 minutes. Results are reported as ML (1+4) at 125° C., where M is Mooney viscosity number, L denotes the large rotor, 1 is the sample preheat time in minutes, 4 is the sample run time in minutes after the motor starts, and 125° C. is the test temperature.

The MLRA data is obtained from the Mooney viscosity measurement when the rubber relaxed after the rotor is stopped. The MLRA is the integrated area under the Mooney torque-relaxation time curve from 1 to 100 seconds. The MLRA can be regarded as a stored energy term which suggests that, after the removal of an applied strain, the longer or branched polymer chains can store more energy and require longer time to relax. Therefore, the MLRA value of a bimodal rubber (the presence of a discrete polymeric fraction with very high molecular weight and distinct composition) or a long chain branched rubber are larger than a broad or a narrow molecular weight rubber when compared at the same Mooney viscosity values.

There are essentially no gels in the present mEPCs based on the fact that the values of GPC-3D mass recovery are all greater than or equal to 90%. Using the DSC second melt experiments, the values of the melting point (T_(m)) and the heat of fusion (H_(f)) of a larger group of these copolymers were determined, FIGS. 1-2. The melting temperature, T_(m), of the polymers were measured using a DSC Q100 equipped with 50 auto-samplers from TA Instruments. This DSC was calibrated with an indium standard weekly. Typically, 6-10 mg of a polymer was sealed in an aluminum pan with a hermetic lid and loaded into the instrument. In a nitrogen environment, the sample was first cooled to -90° C. at 20° C./min The sample was heated to 220° C. at 10° C./min and melting data (first heat) were acquired. This provides information on the melting behavior under “as-received” conditions, which can be influenced by thermal history as well as sample preparation method. The sample was then equilibrated at 220° C. to erase its thermal history.

Crystallization data (first cool) were acquired by cooling the sample from the melt to −90° C. at 10° C./min and equilibrated at −90° C. Finally, the sample was heated again to 220° C. at 10° C./min to acquire additional melting data (second heat). The endothermic melting transition (second heat) was analyzed for peak temperature as Tm and for area under the peak as heat of fusion (Hf).

The mEPCs made by catalyst 1/activator 1 have higher values of T_(m) and H_(f) than the mEPCs made by catalyst 2/activator 2. At an ethylene content of 55 wt %, the mEPC prepared with catalyst 1/activator 1 has a longer methylene sequence than that prepared with catalyst 2/activator 2 based on ¹³C NMR studies, Table 2. This leads to a T_(m) of 30° C. higher for the mEPC prepared with catalyst 1/activator 1 compared to samples from the catalyst 2/activator 2 catalyst system. In Table 2, the values of wt % C₂ of mEPC determined by ¹³C NMR and FTIR are close, at least for these 3 copolymers. The difference is less than or equal to 0.5 wt %. The values of r₁ and r₂ denote the reactivity ratios, which represent the ratios of the rate constants describing the addition of a like monomer relative to an unlike monomer.

If the r₁r₂ value is less than unity as measured for sample 1, it represents more alternating or random sequences. If r₁ and r₂ are both large but not infinite, as shown for sample 2 and sample 3, then block or blocky copolymers will be produced, or perhaps some homopolymers may be present, depending on how large the reactivity ratios are and the relative concentration of the monomers in the feed. Additionally, individual reactivity ratios were estimated from continuous polymerization reactor data (experiments from Table 1 plus additional experiments not reported having a total monomer conversion of 46-53 wt %) using a linear least squares algorithm to fit the data to the standard copolymer equation. Using this method, we estimate r₁=5.22, r₂=0.52, giving r₁r₂=2.71, which is also in good agreement with the reported ¹³C NMR results.

TABLE 1 Process Condition and Characterization of Some mEPCs Prepared with catalyst 1/activator 1 Sample #: 2 4 5 6 7 8 3 Temperature, ° C. 80 80 80 80 80 80 80 Pressure, psig 320 320 320 320 320 320 320 Feed C₂, g/min 2.40 3.12 2.76 2.40 2.03 3.12 3.12 Feed C₃, g/min 3.60 4.80 4.20 3.60 3.00 4.80 4.80 Solvent (isohexane), g/min 61.23 61.23 61.23 61.23 61.23 61.23 61.23 catalyst 1, mol/min 7.34 × 10⁻⁸ 7.34 × 10⁻⁸ 7.34 × 10⁻⁸ 7.34 × 10⁻⁸ 7.34 × 10⁻⁸ 6.43 × 10⁻⁸ 5.51 × 10⁻⁸ activator 1, mol/min 7.49 × 10⁻⁸ 7.49 × 10⁻⁸ 7.49 × 10⁻⁸ 7.49 × 10⁻⁸ 7.49 × 10⁻⁸ 6.56 × 10⁻⁸ 5.62 × 10⁻⁸ Catalyst Activity (g/g) 74,700 114,863 96,187 80,550 66,488 109,286 115,500 Polymer C₂, Wt % (FTIR) 53.3 50.9 51.9 52.3 52.8 53.4 54.8 LS M_(w), kg/mol 240 240 224 201 172 233 235 DRI M_(w)/M_(n) 2.26 2.44 2.34 2.36 2.41 2.40 2.60 g′_(vis) 0.889 0.865 0.884 0.878 0.878 0.913 0.933 GPC-3D Mass 90 94 95 94 97 99 100 Recovery, % ML 47 50 59 48 38 68 82 MLRA 326 529 500 368 276 543 604 T_(m), ° C. −2.7 −1.7 −7.6 −7.9 −6.2 −1.8 1.3 H_(f), J/g 17 11 18 17 17 22 23

TABLE 2 ¹³C NMR Results of mEPCs Sample 1 2 3 Catalyst/Activator 2/2 1/1 1/1 Mol % C₂ (NMR) 65.6 63.0 64.8 Mol % C₃ (NMR) 34.4 37.0 35.2 Wt % C₂ (NMR) 56.0 53.2 55.2 Wt % C₃ (NMR) 44.0 46.8 44.8 Wt % C₂ (FTIR) 55.5 53.3 54.8 Wt % C₃ (FTIR) 44.5 46.7 45.2 Average Sequence 5.9 8.2 8.5 Length for Methylene Sequences Two and Longer Average Sequence 10.3 12.7 13.2 Length for Methylene Sequences Six and Longer r₁r₂ 0.41 2.8 2.8

TABLE 2a Methylene Sequence Length Distribution Methylene Sequence Percentage of Sequences of Length N of Length (N) sample 1 sample 2 sample 3 2 1 1 1 3 42 27 27 4 1 <1 <1 5 23 23 23   6+ 31 48 49

Tables 2 and 2a contain chain punctuation data determined from ¹³C NMR spectra. Chain punctuation can be evaluated using the Run# which represents the number of times that a comonomer changes from one type to the other per 100 monomers. At a given comonomer level a lower Run# indicates that the comonomer is more blocked. Blockiness can also be evaluated by calculating an average methylene sequence length which is determined by dividing the methylene content by the total number of sequences. Therefore, at a particular methylene concentration the average sequence length will necessarily be longer with a lower number of methylene runs or sequences. In Table 2 average sequence length for all methylene sequences 2 and longer and 6 and longer are shown. Sample 1 made with the catalyst 2/activator 2 catalyst system has shorter methylene sequences on average than samples made with catalyst 1/activator 1. The longer sequences in the catalyst 1/activator 1 polymers correlate with their higher level of crystallinity relative to the catalyst 2/activator 2 sample.

Table 2a contains the methylene sequence length distribution in the copolymers determined by ¹³C NMR. Sample 1 made with catalyst 2/activator 2 has a more even distribution of sequences relative the catalyst 1/activator 1 polymers. Catalyst 1/activator 1 samples have a lower percentage of shorter sequences and a higher amount of longer ones compared to the catalyst 2/activator 2 polymer. The greater proportion of longer sequences in the catalyst 1/activator 1 polymers is consistent with them having more crystallinity compared to the catalyst 2/activator 2 polymer.

FIGS. 3-5 show the GPC-3D traces of the 3 mEPCs described in Table 2. No shoulders or extra peaks that would cause the higher T_(m) values for the two mEPCs prepared with catalyst 1/activator 1 were noted.

Table 3 shows the GPC-3D, ML and MLRA results of a set of mEPCs made by catalyst 2/activator 2 or catalyst 1/activator 1. These mEPCs have similar molecular weights or ML and similar C₂ contents. These copolymers have essentially no gel because the values of GPC-3D mass recovery are all greater than or equal to 90%. The mEPCs made by catalyst 1/activator 1 show more branching, as indicated by small values of g′ and a larger values of MLRA. The larger MLRA is due to the fact that, after the release of an applied deformation in the Mooney rheometer, the branched mEPC takes a longer time to relax relative to a linear mEPC, leading to a larger relaxation area under the Mooney torque curve. At similar molecular weights, the mEPCs prepared with catalyst 1/activator 1 also have larger values of tensile strength and elongation at break than the mEPC prepared with catalyst 2/activator 2, FIG. 6.

TABLE 3 GPC-3D and Mooney Viscosity of mEPCs LS LS GPC-3D C₂, Catalyst/ M_(n), M_(w), DRI Mass Re- Wt % Sample Activator kg/mol kg/mol M_(w)/M_(n) g′ covery, % (FTIR) ML MLRA 9 2/2 78 152 2.05 0.993 95 56.3 38 126 7 1/1 73 172 2.41 0.878 97 52.8 38 276 10 1/1 65 144 2.52 0.875 100 52.8 29 177

Additional evidence for the existence of branch structure in mEPCs prepared with catalyst 1/activator 1 is based on ¹H NMR results shown in Table 4, where N is the number of terminal double bonds per chain by assuming any double bond detected by ¹H NMR is at the chain end. The value of N can be determined by the following equation:

N=[(vinyls/1000C)/1,000](M _(n)/14)

The N value of mEPC made using catalyst 1/activator 1 is much higher than that from the catalyst 2/activator 2 sample. There are 75 chains containing the terminal double bond in every 100 chains of the catalyst 1/activator 1-derived mEPC. For the mEPC made with the catalyst 2/activator 2 catalyst system, there are only 4 chains containing the terminal double bond in every 100 chains. The greater number of chains terminating with a double bond can result in more branching by increasing the probability of polymer reincorporation during polymerization.

TABLE 4 Proton NMR Results of mEPCs GPC-3D Catalyst/ LS M_(n), Mass Re- Vinyls/ Sample Activator kg/mol g′ covery, % 1,000 C N 11 2/2 38 0.963 92 0.02 0.05 2 1/1 88 0.889 90 0.12 0.75

Another method to detect the existence of branch structure in these mEPCs is based on small-strain rheology as shown in FIGS. 7a and 7b for the samples prepared using the catalyst 1/activator 1 and catalyst 2/activator 2 catalyst, respectively. In these rheological measurements, the test temperature was 190° C. and the shear strain applied was 10%. The complex modulus (G*), the phase angle (δ), and the complex viscosity (η*) were measured as the frequency was varied from 0.01 to 100 rad/s. The plots of phase angle versus the complex modulus in FIGS. 7a and 7b are known as the Van Gurp-Palmen plots (Please see M. Van Gurp, J. Palmen, Rheol. Bull., 1998, 67, 5-8). The lower the δ, the higher is the melt elasticity or melt strength. Because FIGS. 7a and 7b are in the same scale, it is evident that the phase angles are lower for mEPCs from catalyst 1/activator 1 than from catalyst 2/activator 2 in the region of G* from 10,000 to 100,000 Pa. Therefore, the former set of mEPCs has higher melt strength. The dependence of complex viscosity as a function of frequency can also be determined from these rheological measurements at 190° C., FIGS. 8a and 8b . The following ratio:

[η*(0.1 rds)−η*(100 rds)]/η*(0.1 rds)

was used to measure the degree of shear thinning of the polymeric materials of the embodiments herein, where η*(0.1 rds) and η*(100 rds) are the complex viscosities at frequencies of 0.1 and 100 rds, respectively, measured at 190° C. The higher this ratio, the higher is the degree of shear thinning. The ratios for the mEPCs prepared with catalyst 1/activator 1 range from 0.987 to 0.993, whereas those prepared with catalyst 2/activator 2 range from 0.957 to 0.973. Therefore, the former set of mEPCs has higher degrees of shear thinning, hence better melt processability.

In terms of application, the mEPC prepared with catalyst 1/activator 1 will be a better compatibilizer for the blends of ethylene-based polymers or copolymers and propylene-based polymers or copolymers than the mEPC prepared with catalyst 2/activator 2 because the former type of mEPC has both a longer ethylene sequence and a branched topology.

Examples 12, 13 and 14 were made as above and described in Table 5. This data corresponds to the data in FIGS. 7b and 8b , where Samples 12, 13, and 14 from top to bottom in the legend.

TABLE 5 Cat GPC-3D Activity LS M_(w), DRI Mass Re- C₂, ENB, T_(m), H_(f), T_(g), Sample Cat (g/g) kg/mol M_(w)/M_(n) g′ covery, % Wt % Wt % ° C. J/g ° C. ML MLRA 12 2/2 125,625 243 2.12 1.009 93 62.3 0 −6.0 25 −48 104 317 13 2/2 120,750 211 2.10 1.011 93 60.6 0 −11 23 −50 81 264 14 2/2 107,719 188 1.99 0.993 94 60.1 0 −16 21 −52 57 192 

1. A branched ethylene-propylene copolymer comprising: at least 50% ethylene content by weight as determined by FTIR; a g′_(vis) of less than 0.98; a methylene sequence length of 6 or greater as determined by ¹³C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%; and greater than 50% vinyl chain end functionality is present.
 2. The branched ethylene-propylene copolymer of claim 1, wherein the g′_(vis) is less than 0.95.
 3. The branched ethylene-propylene copolymer of claim 1, wherein the ethylene-propylene copolymer has a ratio of percentage of saturated chain ends to percentage of vinyl chain that is greater than
 1. 4. The branched ethylene-propylene copolymer claim 1, wherein the ethylene-propylene copolymer has a heat of fusion from 5 J/g to 50 J/g.
 5. The branched ethylene-propylene copolymer of claim 1, wherein the ethylene-propylene copolymer T_(m) is from −10° C. to 40° C.
 6. The branched ethylene-propylene copolymer of claim 1, wherein the ethylene-propylene copolymer has a Mooney viscosity (ML) range at 125° C. of from 29 to 100 Mooney units (MU).
 7. The branched ethylene-propylene copolymer of claim 1, wherein the branched ethylene-propylene copolymer has a Mooney large relaxation area (MLRA) of from 100 to
 1000. 8. The branched ethylene-propylene copolymer of claim 1, wherein the r₁r₂ is greater than
 2. 9. The branched ethylene-propylene copolymer of claim 1, wherein the branched ethylene-propylene copolymer has an elongation (break) of at least 150%.
 10. The branched ethylene-propylene copolymer of claim 1, wherein the branched ethylene-propylene copolymer has a nomial stress range of from 0.22 MPa to 0.32 MPa at a 50% strain and 0.15 MPa to 0.2 MPa at 150% strain, at a pull rate of 5.08 centimeters/minute.
 11. The branched ethylene-propylene copolymer of claim 1, wherein the branched ethylene-propylene copolymer ethylene content is from 50% to 55%.
 12. A process for the preparation of the ethylene/propylene branched polymer of claim 1, wherein the process comprises: contacting ethylene and propylene, under polymerization conditions, with at least a catalyst system comprising an activator and at least one metallocene and obtaining a branched ethylene/propylene copolymer having at least 50% ethylene content by weight as determined by FTIR; a g′_(vis) of less than 0.98; a methylene sequence length of 6 or greater as determined by ¹³C NMR, wherein the percentage of sequences of the length of 6 or greater is more than 32%; and greater than 50% vinyl chain end functionality is present.
 13. The process of claim 12, wherein the process is a solution process.
 14. The process of claim 12, wherein the metallocene compound is represented by the formula:

where each R³ is hydrogen; each R⁴ is independently a C₁-C₁₀ alkyl; each R², and R⁷ are independently hydrogen, or C₁-C₁₀ alkyl; each R⁵ and R⁶ are independently hydrogen, or C₁-C₅₀ substituted or unsubstituted hydrocarbyl and R⁴ and R⁵, R⁵ and R⁶ and/or R⁶ and R⁷ may optionally be bonded together to form a ring structure; J is a bridging group represented by the formula Ra₂J, where J is C or Si, and each Ra is, independently C₁ to C₂₀ substituted or unsubstituted hydrocarbyl, and two R^(a) form a cyclic structure incorporating J and the cyclic structure may be a saturated or partially saturated cyclic or fused ring system; and each X is is a univalent anionic ligand, or two Xs are joined and bound to the metal atom to form a metallocycle ring, or two Xs are joined to form a chelating ligand, a diene ligand, or an alkylidene ligand.
 15. The process of claim 12, wherein the metallocene compound is one or more of: cyclotetramethylenesilylenebis(2,4,7-trimethyl-indenyl)hafnium dimethyl, cyclotrimethylenesilylenebis(2,4,7-trimethyl-indenyl)hafnium dimethyl, cyclotetramethylenesilylenebis(2,4,7-trimethyl-indenyl)hafnium dichloride, cyclotrimethylenesilylenebis(2,4,7-trimethyl-indenyl)hafnium dichloride, or mixtures thereof.
 16. The process of claim 12, wherein the activator is dimethylanilinium tetrakisperfluoronaphthylborate. 